What happens in a stress test?

In a stress test, the doctor compares symptoms, your ECG, and images of your heart at rest and after exercising. The heart can be exercised via a treadmill or, if unable to use a treadmill, use chemicals to simulate exercise. You should expect to be present for 2-3 hours. You will need to lay flat, preferably with your arms above your head, for a set of resting images and a second set of images after stress.